eiirenfried corleis and hermann



czar-cost 'bon.

2o ing to the luminosity of the are, but are dis- DUHQLJD" an I siren STATES v PATENT Fri-ca,

EHRENFRIED CORLEIS AND HERMANN RENISCH, OF ESSEN, GERMANY, ASSIGNORS TO THEFIRM OF FRIED. KRUPP, OF SAME PLACE.

MANUFACTURE OF CARBON RODS FOR ELECTRIC-ARC LAMPS.

' SPECIFICATION forming part of Letters Patent No.. 504,105, dated August 29, 1893.

Application filed liprilZG, 1893. Serial No. 471,943. (No specimens.)

To all whom. it may concern.-

Be it known that we, EHRENFRIED CORLEIS' and HERMANN RENIscH, subjects of the King of Prussia, residing at Essen, in the Kingdom of Prussia, Germany, have invented new and useful Improvements in the Manufacture of Carbon Rods for Electric-Arc Lamps, of which the following is a specification.

Ourinvention has reference to an improved electrode or carbon for are lamps, it relating especially to carbons impregnated with a chemical for the purpose of prolonging the life of the same and to increase the intensity of the light.

In the combustion of the ordinary carbons, an annular layer of finely divided carbon particles is formed in pronimity to the arc owing to a secondary combustion of the can These particles are not useful in addsipated or fall down and are wasted, in consequence whereof the carbons are reduced in cross-section and the life of the same is shortened. To remedy this defect carbons have heretofore been impregnated or mixed with phosphate of lime, silicic acid, magnesia, borate and phosphate of magnesia, aluminium oxide, silicate of aluminium, oxide, boric acid,

zinc chloride, copper nitrate, strontium nitrate, hydrate of potash, borax and sulphate of soda, phosphoric acid, and phosphate of ammonia or solutions of the same.

The object of ourin vention is to entirely prevent the secondary combustion, and consequently to increase the intensity of the light and to prolong the life of the carbons. \Vith this object in View we impregnate the carbons with substances such as tungstic acid or its salts which are not consumed at awhite heat, but only in the luminous arc, so that the form assumed by the end of the upper carbon is more favorable for the emission of light.

In carrying out our invention we mix with the paste from which the carbons are subsequently made, tungstic acid or a salt of the same, or to obtain a similar result we impregnate the crude or finished carbons with tungstic acid, or salts of the same. From practical experiments made with impregnated carbons, we have determined that the life of carbons usually burning eighteen hours, is increased to twenty-one hours-the limit ing determined by the lower carbon, as the upper carbon remains in a condition to burn for about two hours longer. By increasing the diameter one millimeter a life of twentythree hours was obtained, so that an increase of from seventeen to twenty-eight per cent. was obtainable.

In practice We have found that impregnation with a solution containing twenty-five per cent. of tungstate of sodium gives good results. 013 the salts adaptable for the purpose of the present invention maybe meneioned as examples tungstate of potassium and tungstate of sodium.

What we claim as uew,and desire to secure by Letters Patent, is

An are light carbon impregnated with tupgstic acid, or a salt of this acid, substantially as described.

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

\ EHRENFRIED OORTJEIS.

HERMANN RENISOH.

Witnesses:

CHRISTIAN SONNENSCHEIN, ALBERT KLINGHAMMER. 

